In the printing machinery industry, synchronous control of multiple motors is a very important issue. Due to the special process requirements of printed products, especially for multi-color printing, in order to ensure the printing overprinting accuracy (generally ≤ 0.05mm), the positional deviation of each motor is required to be very high (generally ≤ 0.02%). In the traditional printing machinery, most of the past used the synchronous control scheme with the mechanical long shaft as the power source, but the mechanical long-axis synchronous control scheme is prone to oscillation phenomenon, each unit interferes with each other, and there are many mechanical parts in the system, which is inconvenient Maintenance and use. With the development of mechatronics technology, fieldbus technology has been applied to various fields and has been widely used.
Synchronization requirements for control systems for shaftless drive presses
The unit type web press is generally composed of a paper feeding unit, a printing unit, a tension unit, a processing unit, and a rewinding unit. In the conventional shaft drive printing machine, the power source is driven by an asynchronous motor through a pulley to drive a mechanical long shaft (about 10-20 m), and then the transmission shafts of the gears, cams, connecting rods, etc. of each unit are driven by the long shaft, and then passed. The transmission component drives the actuator of the device to complete the input and output tasks of the device.
Control system design
Taking into account the complex synchronous motion relationship in the printing press, high precision of overprinting, many printing units, dispersion, multi-operation sub-station, long printing production line, etc., fully distributed, all-digital, fully open fieldbus control system FCS, bus Choose to use the CAN bus.
In order to realize the complex synchronization relationship of each printing unit, the main controller and the servo drive of each motor are connected to the CAN bus to form a CAN field bus system with the printing machine controller as the core, as shown in Fig. 2.
Both the controller and the servo drive are equipped with a CAN bus controller SJA1000 and a transceiver PCA82C250 communication adapter card. The controller can communicate with each servo driver conveniently and quickly through a CAN communication adapter card connected to the printer controller. The control command and the position given command are sent to each servo unit, and the state information of each servo motor is obtained in real time, and the servo parameters are modified in real time as needed, and each servo unit can also perform data exchange in time through the CAN bus. Each servo drive closely follows the position command after obtaining its own position reference command. Since the position command of the controller is directly input to each servo driver, each servo driver obtains a synchronous motion control command, which is not affected by other factors, that is, any servo unit is not affected by the disturbance of other servo units. In this system, the controller and each servo drive act as a network node to form a CAN control network. At the same time, due to the fieldbus control system, the number of network nodes can be expanded according to the printing scale.
